Initially, treatment of HIV infection consisted of monotherapy with nucleoside derivatives and although successful in suppressing viral replication, these drugs quickly lost their effectiveness due to the emergence of drug-resistant strains. It became clear that a high mutation rate combined with rapid replication made HIV a particularly challenging target for antiviral therapy. The introduction of combination therapy of several anti-HIV agents improved therapeutic outcome. The current standard of care is the so-called HAART (Highly Active Anti-Retroviral Therapy), which offers a powerful and sustained viral suppression. HAART typically involves a combination of nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs or NtRTIs respectively) with a non-nucleoside reverse transcriptase inhibitor (NNRTI), a protease inhibitor (PI), and an integrase inhibitor or entry inhibitor. Current guidelines for antiretroviral therapy recommend at least a triple combination therapy regimen even for initial treatment. Although HAART is capable of suppressing HIV up to undetectable levels, resistance can emerge due to compliance problems. It also has been shown that resistant virus is carried over to newly infected individuals, resulting in severely limited therapy options for these drug-naive patients.
Therefore there is a continued need for new and effective compounds that can be used as anti-HIV drugs. In particular, there is need for further HIV integrase inhibitors that are more effective in terms of activity against wild type virus, but also against mutated strains, in particular toward mutated strains selected by known integrase inhibitors such as raltegravir and elvitegravir. Primary mutations most frequently developed during raltegravir therapy include N155H and Q148K/R/H, and infrequently Y143R/C. The acquisition of N155 or Q148 mutations was found to result in cross-resistance to structurally diverse integrase inhibitors. Raltegravir treatment failure is associated with integrase mutations in at least 3 distinct genetic pathways defined by 2 or more mutations including a signature (major) mutation being one of the primary mutations at Q148H/K/R, N155H, or Y143R/H/C, and, one or more additional minor mutations. Minor mutations described in the Q148H/K/R pathway include L74M plus E138A, E138K, or G140S. The most common mutational pattern in this pathway is Q148H plus G140S, which also confers the greatest loss of drug susceptibility. (V. A. Johnson et al. (2009) Topics in HIV Medicine 17(5), 138-145).
There is a need for integrase inhibitors that offer advantages in terms of their pharmacokinetic and/or pharmacodynamic profile. Other aspects that should be considered in the development of further integrase inhibitors include a favorable safety profile, dosing and/or the lack of the need for boosting.
Other HIV integrase inhibitors are known in the art. For instance, WO0255079, WO0230931, WO0230930 and WO0230426 disclose aza- and polyaza-naphthalenyl carboxamides useful as inhibitors of HIV integrase. WO0236734 discloses additionally aza- and polyaza-naphthalenyl ketones useful as inhibitors of HIV integrase. In Roggo et al., Journal of antibiotics (1996), spirodihydrobenzofuranlactams are disclosed as antagonists of endothelin and as inhibitors of HIV-1 protease.
Polycyclic carbamoylpyridones have also been disclosed as inhibitors of HIV integrase in EP1874117. WO2005118593 discloses a series of bicyclic heterocycles as integrase inhibitors, and WO2004103278 discloses a series of acyl sulfonamides as inhibitors of HIV integrase. WO2005028478 discloses a series of aza-quiniolinol phosphonate compounds as integrase inhibitors and WO2004035577a series of pre-organised tricyclic integrase inhibitors. Furthermore, a series of pyridopyrazine and pyrimidopyrazine-dione compounds was disclosed WO2005087766. Additionally, tetrandyro-4H-pyrido (1,2-a) pyrimidines and related compounds were disclosed by Instituto di Ricerche di Biologia Moleculare p Angeletti Spa in WO2004058757. Japan Tobacco Inc have disclosed 4-oxyquinoline compounds as HIV integrase inhibitors in WO2004046115, and a 6-(heterocycle-substituted benzyl)-4-oxoquinoline compound as an HIV inhibitor in US20080207618. WO2005110414 and WO2005110415 disclose hydroxy-substituted pyrazinopyrrolopyridazine dione compounds as inhibitors of HIV integrase and inhibitors of HIV replication.
The present invention is aimed at providing a particular novel series of pyrazinopyrrolo-pyridazine dione derivatives having HIV replication- and HIV integrase-inhibiting properties.